Many people from the 300zx board
have asked what the proper procedure is for sanding/polishing aluminum
(rims, etc...). Here is the best and easiest way:

First, make sure the surface is clean. Use a caustic based all
purpose cleaner. Acid also works very well, but remember that is
does eat through aluminum surfaces so be sure to rinse it off. (Don't
ever use acid on the rims after polishing them).
The factory 300zx rims come with a clearcoat. In order for the
rims to be sanded/polished, the clearcoat must be removed along with the
"machine lines" on the rim. Remove them by wetsanding with 320 grit
sandpaper. It'll take some time and patience. Also, when polishing
the rims, be sure to do only the flat surfaces and the outer edges.
The inner slats should be left how they are, as they create a nice-looking
contrast and would be extremely difficult to sand/polish anyway.
Some surfaces, such as the manifold cover or the throttle body, have a
different texture then the rims. The only difference in polishing
them will be the grit of sandpaper that you will start with.
Sanding can be done either by hand or power sander, but be VERY careful
with a power sander. Adding some padding (like foam) to the backing
is a good idea, since the metal clips on palm sanders tend to gouge the
surface of the rim. Always finish each sanding step by hand to get
any areas the sander may have missed, and be sure to have plenty of fresh
sand paper as it will wear out rather quickly.

To sand the rims:

-wetsand with 320 grit paper
emphasis on 'wet'. Use a lot of water in a spray bottle
(320 grit will leave sand scratches. This is normal....duh!)

-repeat same step with 1,000 grit, then move on to 1,500 grit sandpaper.

Be sure to take your time while sanding and not to miss any areas.
Once the sanding is done...take a high-speed buffer (the more RPM's, the
better) with a coarse 'synthetic' wool pad and buff out all of the 1500
grit sand-scratches with a good buffing compound. I would recommend
3M Perfect-it 2 Rubbing
Compound ...it's pretty good stuff. If you need a little extra
bite, use the 3M medium or heavy cut compound first. It's in the
compounding step that the rims will really start to shine and you'll get
to see how good of a sanding job you did. The key here is to generate
a lot of HEAT with the buffer. This is what removes the sand scratches...it
will not harm the rim in any way. After buffing the rim out completely
with the 3M compound, repeat the procedure with a good aluminum polish.
The best on the market is Mother's California
Gold Aluminum and Mag Polish. Buff it with a high speed buffer
until it gets really shiny. After that is done...just slap a good
coat of wax on the rims to protect them. The best waxes are made
by Meguiars and Mothers
.
This is all a pretty time-consuming process, but it is worth it if
you really want to get complements on your rims. To maintain the
shine, just wax the rims periodically. It only takes about 5 minutes
to wax all 4 rims so do it frequently. If they get dull or accumulate
excessive caked-on dirt, use the Mother's polish by hand or with the buffer
and then wax the rims again. Contrary to popular belief, aluminum rims
are easier to maintain than chrome as they will not rust and can always
be resanded and polished if they get really dull due to neglect.
E-mail me if there are any more questions on polishing aluminum.